®

IMX35 Series Data Sheet

35 Watt Quad-Output DC-DC Converters

BCD20009-G Rev AC, 06-May-2013

Page 9 of 15

Ω

Ω

Ω

Ω]

Trim

Trim1

105 to 108 (107 typically)

0

0

105

10

17

102

62

110

100

∞∞

Auxiliary Functions

Adjustable Output Voltage

As a standard feature, the IMX35 offer adjustable output

schematic diagram for the adjustment of quad-output models.

All models with equal output voltages have a Trim input at pin

5 referenced to the primary side, influencing all outputs simul-

taneously. Models with different output voltages exhibit a

Fig. 13

Output voltage control by means of the Trim input

Trim [V]

Trim1 [V]

>105

0

0

102

1.8

1.5

100

2.5

2.5

95

4.3

4.25

90

6.2

6.2

85

8

8

Synchronization (W)

It is possible to synchronize the switching frequency of one or

more converters to an external clock signal.

This logic input W can be used to synchronize the oscillator to

an external frequency source. This signal is edge-triggered

with TTL thresholds and requires a source frequency of 490 to

540 kHz (duty cycle 10 to 90%). The external source frequency

is internally divided by 2 to define the switching frequency of

the converter. If unused, this pin can be connected to V1– (pin

2) or left open-circuit.

Reference Output (Ref)

The converter provides a stable 5 V (±0.1 V) reference signal

on pin 7 (Ref). The output is protected by a 1 k

Ω resistor. The

signal may be used also in conjunction with the Trim input (pin

5) as a limited external voltage reference.

It is recommended to connect a filter capacitor (0 .1 µF)

between Ref and Vi–, if Ref is used.

Shutdown

The outputs of the converters may be enabled or disabled by

means of a logic signal (TTL, CMOS, etc.) applied to shut-

down (pin 8). If the shutdown function is not required, pin 8

should be left open-circuit:

Converter operating:

2.0 to 20 V

Converter disabled:

–10 to 0.7 V

Adjustment of the output voltage by means of an external

(pin 2). The following table indicates suitable resistor values for

For external output voltage adjustment in the range 85 to

connected to Trim or Trim1 (pin 5) and Vi–. The table below

voltage of 15 to 20 V will set the converter into the hiccup

mode. Direct paralleling of the Trim pins of converters of the

same type connected in parallel is feasible.

Trim

Vo1+

Vo2–

+

V

ext

–

Vi+

Vi–

R

ext

Vo1–

Vo2+

06137c

Control

circuit

V

4

5

2

16

15

13

14